This invention relates to method and apparatus which produce coffee, tea or other beverages during a single cycle. This invention is an improvement in coffee brewing machines as it allows a filter element to be repetitively used and efficiently cleans the filter element and disposes of the grounds which allows the device to remain clean and sanitary.
The present invention is an improvement in single cup beverage brewers such as the ones disclosed in U.S. Pat. No. 3,565,641 issued Feb. 23, 1971, U.S. Pat. No. 4,632,023, issued Dec. 3, 1986 and U.S. Pat. No. 4,694,739 issued Sep. 22, 1987. In these apparatus the filter element consists of filter paper that cannot be reused. The present invention allows the filter element to be reused.
These patents describe methods and apparatus which produce a single cup of coffee which consists of an upper chamber that is open at the top to allow coffee and hot water to enter and be mixed. For most of the cycle the upper chamber is tightly sealed to a lower chamber with a movable filter held therebetween.
The lower chamber contains a piston which can move up and down. The piston first moves upwardly to force air through the mixture of coffee and water in the upper chamber. This air movement agitates the coffee and water. The piston then travels downward and draws the liquid coffee through the filter element. The liquid coffee is drawn down until it reaches an opening in the lower chamber and it pours out along a spout. The chambers are then separated to advance the filter, and the filtered solids consisting of coffee grounds remain on the filter element. Thus, the movable filter becomes used up and must be replaced.
The present invention is also an improvement over beverage machines, such as U.S. Pat. No. 4,903,586, which employs a reusable movable, flexible filter strip as a filter element. In this device when the lower chamber is separated from the upper chamber, the filter strip is removed from the lower chamber and the coffee residue is scraped from the filter element. The filter element is then returned to the lower chamber and is ready for the next cycle. The brewer of this latter patent involves many moving parts in order to remove the coffee grounds. In order to prevent liquids from being ejected from the upper chamber, the filter strip requires a "hold down" mechanism in the upper chamber to clamp the filter during brewing, thereby adding complexity to the brewer and additional moving parts in the most messy part of the apparatus. After each cycle is complete the wet section of filter strip rests at the opposite side of the brewer from the side where the coffee grounds are deposited.
The prior art brewers have a method of adjusting the pressure on the upper chamber to clamp it to the lower chamber. This is done through the addition of spacers or through turning of an adjusting nut. Therefore, these brewers require proper adjustment in order to brew coffee.